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5.7 Missing Values

If NameMapper can not find a Python value for a Cheetah variable name, it will
raise the NameMapper.NotFound exception. You can use the #errorCatcher
directive (section 10.2) or errorCatcher
Template constructor argument (section 4.1) to specify
an alternate behaviour. BUT BE AWARE THAT errorCatcher IS ONLY INTENDED FOR
DEBUGGING!

To provide a default value for a placeholder, write it like this:
$getVar('varName', 'default value'). If you don't specify a default
and the variable is missing, NameMapper.NotFound will be raised.